1. Field of the Invention
This invention relates to a process for filling and sealing a fluid-containing plastic disposable syringe that is to be sterilized, whereby the disposable syringe comprises a barrel with a nozzle part that is molded at the front, an at least one-piece plunger or plunger plug, and a plunger stop element that is placed in the area of the cylinder gripping plate
2. Description of the Prior Art
To date, ampoules and injection vials have primarily been used for parenteral administration of liquid pharmaceutical agents. In addition, a hypodermic syringe with a matching injection cannula is required to administer the liquid or free-flowing substances that are decanted in these containers. This means, however, that the pharmaceutical agent must be transferred to such a hypodermic syringe before final use. This is not only time-consuming but also creates considerable opportunities for contamination.
To keep the liquid pharmaceutical agent from being contaminated, therefore, prefilled disposable syringes are already available on the market. Such a disposable syringe is known from EP-B 0 227 401. There, a process for the production of filled, sterile plastic syringes is described. The disposable syringe, whose design corresponds to DIN 13 098 Part 2, is sterilized in a special process to preserve its geometric shape. To prevent the plastic disposable syringe from being deformed in an autoclave under the action of high internal syringe pressure, the pressure is increased in the autoclave by adding compressed air until the internal syringe pressure is reached.
In addition to a pneumatic pump, this process required a steam generator with low inertia since although the compressed air that is introduced into the autoclave raises the internal autoclave pressure, it considerably lowers the temperature that is necessary for sterilization. It is also disadvantageous that heat transfer is reduced by the presence of air in the air/vapor mixture, which leads to a prolonged retention time in the autoclave.
Another drawback arises from the design of the disposable syringe that is used. It must be filled with the preparation through the opening on its plunger rod side. With this method of filling, a gas bubble is included in the barrel under the plunger plug that is to be used which further increases the internal syringe pressure during sterilization and thus forces the plunger plug to be pushed out and/or the syringe body to deform.
This drawback also exists for a subcutaneous syringe with a partial glass structure that is known from U.S. Pat. No. 5,069,670. The syringe has a glass barrel, a mounted cylinder gripping plate with an internal collar, a mounted head element with a standard connecting part for attaching medical cannulae, a plunger plug, and a sealing part. It cannot be sterilized in the filled state, however, since its glass cylinder cannot withstand high internal pressure during a sterilization process in the autoclave.